"Spelling Mississippi" joke

A bus stops and two obviously Italian men get on. They seat themselves, and engage in animated conversation. The lady sitting behind them ignores their conversation at first, but her attention is galvanized when she hears one of the men say the following: "Emma come first. Den I come. Two asses, they come together. I come again. Two asses, they come together again. I pee twice. Then I come once more." "You foul-mouthed wop swine," retorted the lady indignantly. "In this country we don't talk about our sex lives in public!" "Hey, cool down lady," said the man. "I was only tellin' my friend here how to spell Mississippi."